Zinc Porphyrin/Imidazolium Integrated Multivariate Zirconium Metal-Organic Frameworks for Transformation of CO2 into Cyclic Carbonates

The design and synthesis of metal-organic frameworks (MOFs) enclosed with multiple catalytic active sites is favorable for cooperative catalysis, but is is still challenging. Herein, we developed a sequential postsynthetic ionization and metalation strategy to prepare bifunctional multivariate Zr-MOFs incorporating zinc porphyrin and imidazolium functionalities. Using this facile strategy, tetratopic [5,10,15,20-tetrakis(4-carboxypheny1)porphyrinato]zinc(II) (ZnTCPP) ligands were successfully installed into the cationic Zr-MOF to obtain ZnTCPPC(Br(-))EtimUiO-66. These MTV-MOFs, including TCPPCIm-UiO-66, TCPPC(Br-)Etim-UiO-66, and ZnTCPPC(Br-)Etim-UiO-66, were well characterized and used in CO, capture and conversion into cyclic carbonate from allyl glycidyl ether and CO, under cocatalyst-free and 1 bar CO, pressure conditions. It was found that the structural features and CO, affinity properties of these MTV-MOFs can be tuned by introducing imidazolium groups or doping zinc sites. Additionally, ZnTCPPC(Br-)Etim-UiO-66 exhibited enhanced catalytic activities compared to other MTVMOFs herein for obtaining the 3-allyloxy-1,2-proplyene carbonate product, which was attributed to the cooperative effect of Zn2+ sites and Br ions in this microporous ionic MTV-MOF. ZnTCPPC(Br-)Etim-UiO-66 can be recycled easily and used at least three times.